The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line
The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line
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DOI：
10.1016/j.marchem.2017.01.001
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发表时间：
2017-03-20
期刊：
影响因子：
3
通讯作者：
Zielinski, Oliver
中科院分区：
文献类型：
--
作者：
Beck, Melanie;Reckhardt, Anja;Zielinski, Oliver
本研究采用跨学科的方法解决了高能海滩系统的关键过程。我们评估地下孔隙水停留时间，盐度，有机质（OM）的可用性和氧化还原条件及其对营养循环的影响，以及微生物群落模式和microphytobenthos生长的空间变化。在北海南部Spiekeroog岛的研究现场，海滩水文的特点是典型的分带与上部盐羽（USP），盐水楔，和淡水排放管之间。沉积物和孔隙水样品采取了沿着从沙丘到低潮线达到沉积物深度下5米沉积物表面的跨海岸横断面。孔隙水停留时间，盐度和有机质的可用性的空间变化导致陡峭的氧化还原和营养梯度。微生物群落的垂直和水平差异表明这些梯度和盐度对群落结构的影响。通过USP的模拟海水通量和通过管道的淡水通量平均分别为每天2.8和0.75米（3）和米的海岸线。此外，在较低的海滩的山脊沉积物排放海水的速率为0.5和1.0米（3）每天和米的海岸线向河道和海滨，分别。应用海水和淡水通量和代表性的营养盐浓度的排放区，营养盐通量到邻近的近岸沃茨是117 mmol NI 4+，55 mmol PO 43-和575 mmol Si（OH）（4）每天和米的海岸线。我们建议，这种营养物质流出触发的排放区沉积物表面上的microphytobenthos的增长。营养物排放率的海滩网站与附近的桑迪backbarrier潮滩边缘的第一次比较表明，海滩系统可能是不太重要的，在供应循环营养物的近岸沃茨比backbarrier潮滩地区。(C)2017爱思唯尔B. V.保留所有权利。
This study addresses key processes in high-energy beach systems using an interdisciplinary approach. We assess spatial variations in subsurface pore water residence times, salinity, organic matter (OM) availability, and redox conditions and their effects on nutrient cycles as well as on microbial community patterns and microphytobenthos growth. At the study site on Spiekeroog Island, southern North Sea, beach hydrology is characterized by the classical zonation with an upper saline plume (USP), a saltwater wedge, and a freshwater discharge tube in between. Sediment and pore water samples were taken along a cross-shore transect from the dunes to the low-water line reaching sediment depths down to 5 m below sediment surface. Spatial variations in pore water residence time, salinity, and organic matter availability lead to steep redox and nutrient gradients. Vertical and horizontal differences in the microbial community indicate the influence of these gradients and salinity on the community structure. Modeled seawater flux through the USP and freshwater flux through the tube are on average 2.8 and 0.75 m(3) per day and meter of shoreline, respectively. Furthermore, ridge sediments at the lower beach discharge seawater at rates of 0.5 and 1.0 m(3) per day and meter of shoreline towards the runnel and seaside, respectively. Applying seawater and freshwater fluxes and representative nutrient concentrations for the discharge zones, nutrient fluxes to adjacent nearshore waters are 117 mmol NI4+, 55 mmol PO43- and 575 mmol Si(OH)(4) per day and meter of shoreline. We propose that this nutrient efflux triggers growth of microphytobenthos on sediment surfaces of the discharge zone. A first comparison of nutrient discharge rates of the beach site with a nearby sandy backbarrier tidal flat margin indicates that the beach system might be of less importance in supplying recycled nutrients to nearshore waters than the backbarrier tidal flat area. (C) 2017 Elsevier B.V. All rights reserved.